A subliminal message is a signal or message designed to pass below the normal limits of perception. For example it might be inaudible to the conscious mind (but audible to the unconscious or deeper mind) or might be an image transmitted briefly and unperceived consciously and yet perceived unconsciously.
The term subliminal message was popularized in a 1957 book entitled “The Hidden Persuaders” by Vance Packard. This book detailed a study of movie theaters that supposedly used subliminal commands to increase the sales of popcorn and Coca-Cola at their concession stands. However, the study was fabricated, as the author of the study James Vicary later admitted.
Subliminal perception or cognition is a subset of unconscious cognition where the forms of unconscious cognition also include attending to one signal in a noisy environment while unconsciously keeping track of other signals (e.g one voice out of many in a crowded room) and tasks done automatically (e.g. driving a car).
Subliminal messages might gain their potential influence/power from the fact that they may be able to avoid the critical functions of the conscious mind. This route to influence would be similar to auto-suggestion or hypnosis wherein the subject is encouraged to be relaxed so that suggestions are directed to deeper parts of the mind.
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